/*
 * Copyright (C) 2022 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

export class Md5 {

    /**
     * Hash a UTF-8 string on the spot
     * @param str String to hash
     * @param raw Whether to return the value as an `Int32Array`
     */
    public static hashStr(str: string, raw?: false): string;
    public static hashStr(str: string, raw: true): Int32Array;
    public static hashStr(str: string, raw: boolean = false) {
        return this.onePassHasher
            .start()
            .appendStr(str)
            .end(raw);
    }
        // Private Static Variables
    private static stateIdentity = new Int32Array([1732584193, -271733879, -1732584194, 271733878]);
    private static buffer32Identity = new Int32Array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
    private static hexChars = '0123456789abcdef';
    private static hexOut: string[] = [];

    // Permanent instance is to use for one-call hashing
    private static onePassHasher = new Md5();

    private static _hex(x: Int32Array): string {
        const hc = Md5.hexChars;
        const ho = Md5.hexOut;
        let n;
        let offset;
        let j;
        let i;

        for (i = 0; i < 4; i += 1) {
            offset = i * 8;
            n = x[i];
            for (j = 0; j < 8; j += 2) {
                ho[offset + 1 + j] = hc.charAt(n & 0x0F);
                n >>>= 4;
                ho[offset + 0 + j] = hc.charAt(n & 0x0F);
                n >>>= 4;
            }
        }
        return ho.join('');
    }

    private static _md5cycle(x: Int32Array|Uint32Array, k: Int32Array|Uint32Array) {
        let a = x[0];
        let b = x[1];
        let c = x[2];
        let d = x[3];
        // ff()
        a += (b & c | ~b & d) + k[0] - 680876936 | 0;
        a = (a << 7 | a >>> 25) + b | 0;
        d += (a & b | ~a & c) + k[1] - 389564586 | 0;
        d = (d << 12 | d >>> 20) + a | 0;
        c += (d & a | ~d & b) + k[2] + 606105819 | 0;
        c = (c << 17 | c >>> 15) + d | 0;
        b += (c & d | ~c & a) + k[3] - 1044525330 | 0;
        b = (b << 22 | b >>> 10) + c | 0;
        a += (b & c | ~b & d) + k[4] - 176418897 | 0;
        a = (a << 7 | a >>> 25) + b | 0;
        d += (a & b | ~a & c) + k[5] + 1200080426 | 0;
        d = (d << 12 | d >>> 20) + a | 0;
        c += (d & a | ~d & b) + k[6] - 1473231341 | 0;
        c = (c << 17 | c >>> 15) + d | 0;
        b += (c & d | ~c & a) + k[7] - 45705983 | 0;
        b = (b << 22 | b >>> 10) + c | 0;
        a += (b & c | ~b & d) + k[8] + 1770035416 | 0;
        a = (a << 7 | a >>> 25) + b | 0;
        d += (a & b | ~a & c) + k[9] - 1958414417 | 0;
        d = (d << 12 | d >>> 20) + a | 0;
        c += (d & a | ~d & b) + k[10] - 42063 | 0;
        c = (c << 17 | c >>> 15) + d | 0;
        b += (c & d | ~c & a) + k[11] - 1990404162 | 0;
        b = (b << 22 | b >>> 10) + c | 0;
        a += (b & c | ~b & d) + k[12] + 1804603682 | 0;
        a = (a << 7 | a >>> 25) + b | 0;
        d += (a & b | ~a & c) + k[13] - 40341101 | 0;
        d = (d << 12 | d >>> 20) + a | 0;
        c += (d & a | ~d & b) + k[14] - 1502002290 | 0;
        c = (c << 17 | c >>> 15) + d | 0;
        b += (c & d | ~c & a) + k[15] + 1236535329 | 0;
        b = (b << 22 | b >>> 10) + c | 0;
        // gg()
        a += (b & d | c & ~d) + k[1] - 165796510 | 0;
        a = (a << 5 | a >>> 27) + b | 0;
        d += (a & c | b & ~c) + k[6] - 1069501632 | 0;
        d = (d << 9 | d >>> 23) + a | 0;
        c += (d & b | a & ~b) + k[11] + 643717713 | 0;
        c = (c << 14 | c >>> 18) + d | 0;
        b += (c & a | d & ~a) + k[0] - 373897302 | 0;
        b = (b << 20 | b >>> 12) + c | 0;
        a += (b & d | c & ~d) + k[5] - 701558691 | 0;
        a = (a << 5 | a >>> 27) + b | 0;
        d += (a & c | b & ~c) + k[10] + 38016083 | 0;
        d = (d << 9 | d >>> 23) + a | 0;
        c += (d & b | a & ~b) + k[15] - 660478335 | 0;
        c = (c << 14 | c >>> 18) + d | 0;
        b += (c & a | d & ~a) + k[4] - 405537848 | 0;
        b = (b << 20 | b >>> 12) + c | 0;
        a += (b & d | c & ~d) + k[9] + 568446438 | 0;
        a = (a << 5 | a >>> 27) + b | 0;
        d += (a & c | b & ~c) + k[14] - 1019803690 | 0;
        d = (d << 9 | d >>> 23) + a | 0;
        c += (d & b | a & ~b) + k[3] - 187363961 | 0;
        c = (c << 14 | c >>> 18) + d | 0;
        b += (c & a | d & ~a) + k[8] + 1163531501 | 0;
        b = (b << 20 | b >>> 12) + c | 0;
        a += (b & d | c & ~d) + k[13] - 1444681467 | 0;
        a = (a << 5 | a >>> 27) + b | 0;
        d += (a & c | b & ~c) + k[2] - 51403784 | 0;
        d = (d << 9 | d >>> 23) + a | 0;
        c += (d & b | a & ~b) + k[7] + 1735328473 | 0;
        c = (c << 14 | c >>> 18) + d | 0;
        b += (c & a | d & ~a) + k[12] - 1926607734 | 0;
        b = (b << 20 | b >>> 12) + c | 0;
        // hh()
        a += (b ^ c ^ d) + k[5] - 378558 | 0;
        a = (a << 4 | a >>> 28) + b | 0;
        d += (a ^ b ^ c) + k[8] - 2022574463 | 0;
        d = (d << 11 | d >>> 21) + a | 0;
        c += (d ^ a ^ b) + k[11] + 1839030562 | 0;
        c = (c << 16 | c >>> 16) + d | 0;
        b += (c ^ d ^ a) + k[14] - 35309556 | 0;
        b = (b << 23 | b >>> 9) + c | 0;
        a += (b ^ c ^ d) + k[1] - 1530992060 | 0;
        a = (a << 4 | a >>> 28) + b | 0;
        d += (a ^ b ^ c) + k[4] + 1272893353 | 0;
        d = (d << 11 | d >>> 21) + a | 0;
        c += (d ^ a ^ b) + k[7] - 155497632 | 0;
        c = (c << 16 | c >>> 16) + d | 0;
        b += (c ^ d ^ a) + k[10] - 1094730640 | 0;
        b = (b << 23 | b >>> 9) + c | 0;
        a += (b ^ c ^ d) + k[13] + 681279174 | 0;
        a = (a << 4 | a >>> 28) + b | 0;
        d += (a ^ b ^ c) + k[0] - 358537222 | 0;
        d = (d << 11 | d >>> 21) + a | 0;
        c += (d ^ a ^ b) + k[3] - 722521979 | 0;
        c = (c << 16 | c >>> 16) + d | 0;
        b += (c ^ d ^ a) + k[6] + 76029189 | 0;
        b = (b << 23 | b >>> 9) + c | 0;
        a += (b ^ c ^ d) + k[9] - 640364487 | 0;
        a = (a << 4 | a >>> 28) + b | 0;
        d += (a ^ b ^ c) + k[12] - 421815835 | 0;
        d = (d << 11 | d >>> 21) + a | 0;
        c += (d ^ a ^ b) + k[15] + 530742520 | 0;
        c = (c << 16 | c >>> 16) + d | 0;
        b += (c ^ d ^ a) + k[2] - 995338651 | 0;
        b = (b << 23 | b >>> 9) + c | 0;
        // ii()
        a += (c ^ (b | ~d)) + k[0] - 198630844 | 0;
        a = (a << 6 | a >>> 26) + b | 0;
        d += (b ^ (a | ~c)) + k[7] + 1126891415 | 0;
        d = (d << 10 | d >>> 22) + a | 0;
        c += (a ^ (d | ~b)) + k[14] - 1416354905 | 0;
        c = (c << 15 | c >>> 17) + d | 0;
        b += (d ^ (c | ~a)) + k[5] - 57434055 | 0;
        b = (b << 21 | b >>> 11) + c | 0;
        a += (c ^ (b | ~d)) + k[12] + 1700485571 | 0;
        a = (a << 6 | a >>> 26) + b | 0;
        d += (b ^ (a | ~c)) + k[3] - 1894986606 | 0;
        d = (d << 10 | d >>> 22) + a | 0;
        c += (a ^ (d | ~b)) + k[10] - 1051523 | 0;
        c = (c << 15 | c >>> 17) + d | 0;
        b += (d ^ (c | ~a)) + k[1] - 2054922799 | 0;
        b = (b << 21 | b >>> 11) + c | 0;
        a += (c ^ (b | ~d)) + k[8] + 1873313359 | 0;
        a = (a << 6 | a >>> 26) + b | 0;
        d += (b ^ (a | ~c)) + k[15] - 30611744 | 0;
        d = (d << 10 | d >>> 22) + a | 0;
        c += (a ^ (d | ~b)) + k[6] - 1560198380 | 0;
        c = (c << 15 | c >>> 17) + d | 0;
        b += (d ^ (c | ~a)) + k[13] + 1309151649 | 0;
        b = (b << 21 | b >>> 11) + c | 0;
        a += (c ^ (b | ~d)) + k[4] - 145523070 | 0;
        a = (a << 6 | a >>> 26) + b | 0;
        d += (b ^ (a | ~c)) + k[11] - 1120210379 | 0;
        d = (d << 10 | d >>> 22) + a | 0;
        c += (a ^ (d | ~b)) + k[2] + 718787259 | 0;
        c = (c << 15 | c >>> 17) + d | 0;
        b += (d ^ (c | ~a)) + k[9] - 343485551 | 0;
        b = (b << 21 | b >>> 11) + c | 0;

        x[0] = a + x[0] | 0;
        x[1] = b + x[1] | 0;
        x[2] = c + x[2] | 0;
        x[3] = d + x[3] | 0;
    }

    private _dataLength = 0;
    private _bufferLength = 0;

    private _state: Int32Array = new Int32Array(4);
    private _buffer: ArrayBuffer = new ArrayBuffer(68);
    private _buffer8: Uint8Array;
    private _buffer32: Uint32Array;

    constructor() {
        this._buffer8 = new Uint8Array(this._buffer, 0, 68);
        this._buffer32 = new Uint32Array(this._buffer, 0, 17);
        this.start();
    }

    /**
     * Initialise buffer to be hashed
     */
    public start() {
        this._dataLength = 0;
        this._bufferLength = 0;
        this._state.set(Md5.stateIdentity);
        return this;
    }

    /**
     * Append a UTF-8 string to the hash buffer
     * @param str String to append
     */
    public appendStr(str: string) {
        const buf8 = this._buffer8;
        const buf32 = this._buffer32;
        let bufLen = this._bufferLength;
        let code;
        let i;
        for (i = 0; i < str.length; i += 1) {
            code = str.charCodeAt(i);
            if (code < 128) {
                buf8[bufLen++] = code;
            } else if (code < 0x800) {
                buf8[bufLen++] = (code >>> 6) + 0xC0;
                buf8[bufLen++] = code & 0x3F | 0x80;
            } else if (code < 0xD800 || code > 0xDBFF) {
                buf8[bufLen++] = (code >>> 12) + 0xE0;
                buf8[bufLen++] = (code >>> 6 & 0x3F) | 0x80;
                buf8[bufLen++] = (code & 0x3F) | 0x80;
            } else {
                code = ((code - 0xD800) * 0x400) + (str.charCodeAt(++i) - 0xDC00) + 0x10000;
                if (code > 0x10FFFF) {
                    throw new Error('Unicode standard supports code points up to U+10FFFF');
                }
                buf8[bufLen++] = (code >>> 18) + 0xF0;
                buf8[bufLen++] = (code >>> 12 & 0x3F) | 0x80;
                buf8[bufLen++] = (code >>> 6 & 0x3F) | 0x80;
                buf8[bufLen++] = (code & 0x3F) | 0x80;
            }
            if (bufLen >= 64) {
                this._dataLength += 64;
                Md5._md5cycle(this._state, buf32);
                bufLen -= 64;
                buf32[0] = buf32[16];
            }
        }
        this._bufferLength = bufLen;
        return this;
    }

    /**
     * Hash the current state of the hash buffer and return the result
     * @param raw Whether to return the value as an `Int32Array`
     */
    public end(raw: boolean = false) {
        const bufLen = this._bufferLength;
        const buf8 = this._buffer8;
        const buf32 = this._buffer32;
        const i = (bufLen >> 2) + 1;

        this._dataLength += bufLen;
        const dataBitsLen = this._dataLength * 8

        buf8[bufLen] = 0x80;
        buf8[bufLen + 1] = buf8[bufLen + 2] = buf8[bufLen + 3] = 0;
        buf32.set(Md5.buffer32Identity.subarray(i), i);

        if (bufLen > 55) {
            Md5._md5cycle(this._state, buf32);
            buf32.set(Md5.buffer32Identity);
        }

        // Do the final computation based on the tail and length
        // Beware that the final length may not fit in 32 bits so we take care of that
        if (dataBitsLen <= 0xFFFFFFFF) {
            buf32[14] = dataBitsLen;
        } else {
            const matches = dataBitsLen.toString(16).match(/(.*?)(.{0,8})$/);
            if (matches === null) {
                return;
            }

            const lo = parseInt(matches[2], 16);
            const hi = parseInt(matches[1], 16) || 0;

            buf32[14] = lo;
            buf32[15] = hi;
        }

        Md5._md5cycle(this._state, buf32);

        return raw ? this._state : Md5._hex(this._state);
    }
}

if (Md5.hashStr('hello') !== '5d41402abc4b2a76b9719d911017c592') {
    throw new Error('Md5 self test failed.');
}
